A number signifying how well a material can refract light. Usually specified as n by scientists, the index of refraction of a material depends on its composition and density. Water has an index of refraction of 1.333; n of air is nearly 1.0; and n of a vacuum is exactly 1.0.

The index of refraction is the ratio of the speed an electromagnetic wave in vacuum to the speed of the electromagnetic wave in a particular medium. typically denoted by the lowercase . n = c/v. The index of refraction is a property of the medium in question, and the incident electromagnetic wave. In general, they index of refraction may depend on on the frequency of the incident wave, and on its polarization. A media in which the index of refraction depends on the frequency of the electromagnetic wave is said to be dispersive. A media in which the index of refraction depends on the polarization of the incident wave is said to be birefringent

The ratio of the speed of light in air to its velocity in another medium; determines how much light bends as it passes through a lens, e.g., high-index flint glass bends light more than low-index crown glass does.

The ratio of the speed of light in vacuum to the speed of light in the medium being considered. Also determines how much the path followed by light bends, or refracts, when traveling from one medium to another. Index of refraction is introduced on this page of this module.

(in'-dex of re-frac'-tion) The ratio of the velocity of light in a vacuum to the velocity of light within a substance. The index of refraction is a function of temperature, pressure and wavelength of light. Birefringent substances, that is, all substances that are anisotropic, have more than one index of refraction. Isometric minerals and amorphous mineraloids are isotropic, that is, their properties are the same in all directions. All other minerals and materials have optical properties that vary with crystallographic direction.

A numerical value indicating the degree of refraction of a medium, expressed by the formula n=sin i/sin r is a constant which is unrelated to the light ray's angle of incidence and indicates the refractive index of the refracting medium with respect to the medium from which the light impinges. For general optical glass, "n" usually indicates the index of refraction of the glass with respect to air.

Ratio of the velocity of light in one medium to its velocity in a second medium as the light passes from medium to medium. If a medium is crystalline the velocity may depend on the direction of the light with respect to the crystalline axes and the substance may have several indexes of refraction i.e. it may be birefringent. (Also see BIREFRINGENCE.)

A measure of the ability of a lens material to refract a ray of light of a given wavelength. This is usually stated for the wavelength of the helium d-line (587.56 nanometers). The higher the index, the more the refractive power of the lens. For the ophthalmic glasses most commonly in use, n=1.5230. The index of refraction for allyl resin, a plastic most commonly used for eyeglasses, is typically 1.4975.

is a ratio between the angle of incidence to the angle of refraction of light. It depends upon the density of a medium. A denser medium will have a higher index of refraction and will also bend the light more.

The index of refraction (or refractive index) of a material is the ratio of the speed of light in a vacuum to the speed of light through a given material. The index of refraction is generally used in particle sizing applications using laser light scattering.

The index of refraction of a medium is the ratio of the speed of light in vacuum to the speed of light in the medium. Also called “refractive index.” See also: fiber, core, cladding, total internal reflection

Also known as refractive index, it expresses how much light is slowed down, and therefore bent, as it enters a substance. A high index of refraction means that light travels slowly in a mineral and is bent more. Index of refraction often varies as the chemical composition does, so a range is given.